During the first hours of the deadly October wildfires, Sonoma County failed to connect with 54 percent of telephone numbers in a database used to send government alerts to the public during emergencies, according to new data released by the county Friday.

The performance of the county’s warning system, SoCo Alert, was hindered by damaged cellphone towers and burned utility lines, said Chris Helgren, the county’s emergency services manager. The damage decreased capacity in the telecommunications system at a time when demand was the greatest, Helgren said.

“During disasters it’s not uncommon to have lower success rates,” he said. “You’re not going to have the same kind of numbers you would when the system is whole.”

Logs detailing emergency communications during the first week of the firestorms — including alerts sent to residents, lists of 911 calls that poured into dispatchers and summaries of communications with first responders — were released Friday by Sonoma County in response to public records requests made by The Press Democrat and other news outlets.

Residents must register with the county to have SoCo Alerts sent to a mobile phone or by email and text message. Landline numbers are automatically entered into the database by the county.

Sonoma County Fire and Emergency Services has faced criticism for failing to notify residents of fast-moving fires, which killed 24 people and destroyed more than 5,130 homes in the county. Many residents claim their first warning came from neighbors or from the roar of gusting winds.

The first SoCo Alert warning of wildfire was sent at 11:37 p.m. — about four hours after the fires broke out — to people in an area from Larkfield east to the Napa County border.

Over the next 24 hours, emergency officials placed 171,724 automated warning calls in Sonoma County, records show. The warnings reached only 27,456 telephone numbers, triggering automatic redials — often multiple times — for most calls that did not go through.

Excluding redials, emergency officials placed warning calls to 55,091 targeted telephone numbers during that period. Records show the warnings failed to reach 29,808 telephone numbers, or 54 percent of the phone numbers targeted by emergency officials. The totals may include numbers targeted more than once.

Records show the county also sent 2,782 emergency emails and 3,558 text messages to residents through SoCo Alert during the 24-hour period.

The data released Friday by the county shows the performance of the warning system declined as the chaos unfolded during the night. The first warning was sent to 2,096 phone numbers on file for the targeted area. The alerts were received by 62 percent of the numbers on file — 1,304.

It is not known how many of those numbers were landlines and how many were cellphone numbers because the system does not distinguish between the two, Helgren said.

“We see a higher success rate on the first call because the fires hadn’t caused as much damage yet,” Helgren said.

The new batch of public records released by the county also detail Nixle alerts sent by both text and email. Nixle postings have been online since the time they were created, but the new records show the reach the messages had at the time.

EDITOR'S NOTE: Audio files, texts and emails of warnings made through the SoCo Alert system were published online Friday by the County of Sonoma. An earlier version of this story incorrectly said the materials had not been released. A county official interviewed for the story did not disclose plans to publish the materials later Friday after a related release of SoCo Alert telephone logs.